湘江特大桥双壁钢套箱围堰受力分析及优化处理  

Mechanical Analysis and Optimal Treatment of Double-Wall Steel Boxed Cofferdams of a Xiangjiang River Bridge

作　　者：杨美良[1] 陈丹[1] 夏桂云[1] 钟放平 

机构地区：[1]长沙理工大学土木与建筑学院,湖南长沙410004 [2]湖南省长湘高速公路建设开发有限公司,湖南长沙410209

出　　处：《桥梁建设》2012年第4期39-44,共6页Bridge Construction

基　　金：交通运输部京珠复线长沙至湘潭高速公路两型科技示范工程项目(CXKJSF0108);长沙理工大学博士启动基金项目~~

摘　　要：长湘高速公路湘江特大桥主桥为(115+195+115)m三跨预应力混凝土连续刚构桥,该桥58号、59号主墩承台采用无底双壁钢套箱围堰施工。为使围堰结构合理、施工安全,采用三维有限元软件ANSYS对该桥58号、59号主墩承台围堰进行结构分析,并结合施工现场的特点,对围堰结构进行优化处理。结果表明:围堰封底混凝土达到80%设计强度并进行堰内抽水时为最不利工况;增大环板厚度使围堰结构受力明显减小;围堰夹壁内填充混凝土较填充水可有效减少结构的最大应力和变形、提高结构的刚度和稳定性;围堰最可能的失效模式为钢围堰连同封底混凝土一起上浮,增加封底混凝土与桩护筒间的握裹力(采取围堰压重、堰壁内灌水等措施)有利于提高围堰抗浮稳定性。实践证明优化措施取得了良好的效果。The main bridge of the Xiangjiang River Bridge on Changsha-Xiangtan Expressway is a 3-span prestressed concrete continuous rigid-frame bridge with span arrangement （115 ＋ 195 ＋115） m. The pile caps of the main piers No. 58 and No. 59 of the bridge were constructed by the double-wall steel boxed cofferdams without bottom. To ensure that the cofferdams were structurally rational and the construction would proceed safely, the three-dimensional finite element software ANSYS was used to analyze the cofferdam structures and also in the light of the site con- struction characteristics, the cofferdams were optimally treated. The results of the analysis reveal that the most unfavorable load case of the cofferdams is at the time when the base sealing concrete for the cofferdams reaches 80% of its designed strength and when water inside the cofferdams is pumped out. The increase of thickness of the surrounding plates can significantly reduce the force in the cofferdams. The filling of concrete into the walls of the cofferdams can effectively reduce the maximum stress and deformation and can increase the rigidity and stability of the cofferdams as compared to the filling of water. The most possible failure mode of the cofferdams is the floating-up of the cofferdams together with their base sealing concrete. The increase of binding forcebetween the base sealing concrete and steel casings （the measures of ballasting on the cofferdams and filling of water into the walls of the cofferdams are taken） is helpful to the floating resistance stability of the cofferdams. Practice proves that sound effect of the optimal treatment of the colferdams has been achieved.

关 键 词：连续刚构桥 承台 围堰 受力分析 优化 措施 有限元法 

分 类 号：U443.162[建筑科学—桥梁与隧道工程]